There is a conventionally known technology for heating a material such as metal or a thin film of such a material by microwave. As an example, as disclosed in Patent Document 1, a thin film formed of an inorganic metal salt which is a precursor of a metal oxide semiconductor, is subjected to microwave irradiation under the atmospheric pressure to convert the thin film to a semiconductor.
Patent Document 2 discloses a technology for promoting densification and crystallization by selective heating of a specific layer on a film substrate, wherein a microwave source is pulse-driven to irradiate pulsed microwave.